Compared to legacy cellular communication which takes place between User Equipment (“UE”) and networks, Device-to-Device (“D2D”) communication, which is also referred to as Proximity-based Service (“ProSe”) communication, enables direct link communication between UEs and thus achieves the potential benefits of UE power saving due to short transmission distances, efficient radio resource reuse and offloading network's burden. The existing third Generation Partnership Project (“3GPP”) Long Term Evolution (“LTE”) network has well-defined mechanisms for maintaining Evolved Packet System (“EPS”) services. When the 3GPP considers integrating D2D features into the LTE network, how to maintain D2D service continuity under continuous network management and control becomes challenging from the perspectives of both end users and operators.